Piston ring



July 27, 1943. E BRQTHWEILER 2,325,196

PISTON RING Filed Jan. 15, 1940 2 Sheets-Sheet l July 27, 1943 E. B.ROTHWEILER PISTON RING Filed Jan. l5, 1940 2 Sheets-Sheet 2 Mv /I/APatented July 27, 1943 PISTON RING Edward B. Rottweiler, st. Louis,'Mo.,

assigner to Coil Piston Ring Company of America, St. Louis, Mo., acorporation of Missouri Application January 13, 1940, Serial No. 313,6463 Claims. (Cl. 309-45) This invention relates to piston rings.

An object of the invention is to provide an improved piston ring made ofa coiled strip or coiled strips of steel of approximately uniformthickness throughout its or their length and including outer andintermediate convolutions having their outer edges on approximatelyuniform radii of curvature, the outer convolutions having approximatelyflat sides throughout their circumferential length, and the intermediateconvolution being arched or bent laterally in a direction approximatelyparallel with the axis of the ring to provide oppositely extendedcontacting portions for contacting with the inner surfaces of the sideconvolutions to hold the side convolutions in spaced relationship and toprovide openings or oil drainage passages through the ring between theouter and inner convolutions.

Another object of the invention is to provide an improved piston ringcomprising a plurality of convolutions of coiled steel, the outerconvolutions being approximately flat throughout. their circumferentiallength and having their ends terminating at relatively short distancesfrom laterally extended portions integrally uniting the outerconvolutions with the intermediate convolution, the intermediateconvolutions being arched or bent laterally to provide a cellularstructure between the outer convolutions, affording spaces for oildrainage when the ring is under compression on a piston within acylinder.

Another object of the invention is to provide an improved piston ringincluding a coiled strip of steel of approximately uniform thicknesshaving an intermediate convolution provided with laterally bent archformations of novel arrangement so that, when the ring is undercompression within a cylinder, the points of the arches are within theradius of curvature of the remaining portion of the ring, therebypreventing the points of the arches from scoring or marring the innersurface of the cylinder when the ring is mounted on a piston therein foruse.

Various other objects and advantages of the invention will be apparentfrom the following description, reference being made to the annexeddrawings, in which- Fig. 1 is a perspective view of a unitary pistonring made in accordance with this invention and distended in order toshow the arch formation of the intermediate convolution.

Fig. 2 is a side elevation of the piston ring in its natural form beforebeing compressed within a cylinder.

Fig. 3 is a sectional view of the piston ring mounted on a piston withina cylinder.

Fig. 4 is a side elevation of a slightly modified form of the ring shownin Fig. 2.

Fig. 5 is a perspective view similar to Fig. 1 showing a piston ringcomposed of two convoluted sections of coiled steel strip.

Fig. 6 is a perspective View of a piston ring, distended as in Fig. 1,showing a modified form of the invention.

Fig. 7 is a side elevation of the piston ring of Fig. 6 in its naturalform before being compressed within a cylinder.

Fig. 8 is a sectional view of this form of piston ring mounted on apiston within a. cylinder.

Fig. 9 is a side elevation of a ring having additional offsetsconnecting the side convolutions with the intermediate convolution andelongated supports for the end portions of the side convolutions.

Fig. 10 is a distended perspective view of a piston ring in whicllli oneof the side convolutions is unattached to t e intermediate convolutionand provided with means coacting m'th the intermediate convolution tolimit extent of relative turning movements of the two parts of the ring.

Fig. l1 is a side elevation of the ring that is shown in Fig. 10.

The piston ring shown in Figs. 1 and 2 is made of a strip of fiat steelrolled or coiled to form a number of convolutionsl including two at sideor end convolutions I and 2 and at least one intermediate convolutionhaving integral connection with the end convolutions and provided withan annular series of lateral arches or bends extending in a directionapproximately parallel with the axis of the ring to provide oppositelyextended spacer portions. The intermediate or spacer convolution of theunitary ring shown in Figs. 1 and 2 includes the circumferentiallyelongated arch portions 3 for contacting the convolution I, and thecircumferenti'ally elongated arch portions 4 for contacting theconvolution 2, and connecting means 5 integrally uniting the archportions 3 and 4. In this form ofthe device, the dat convolution I isintegrally united with the arch portion 3 at the adjacent end of theintermediate convolution by an integral connection 6 inclining laterallyfrom the arch portion 3 to the convolution I, The attached end of theconvolution I is offset laterally from the part 3 a distanceapproximately equal to the thickness of said convolution I so that, whenthe ring is placed within the piston ring groove 1 (Fig. 3), the outerside of the convolution I is pressed against one of the side walls ofsaid groove.

The attached end of the outer convolution 2 is integrally'united withthe adjacent end of the portion 4 by a lateral bend 8 similar to theconnection 6 so that, when the ring is compressed in a piston groove,the entire outer surface of the convolution 4 contacts with one wall ofsaid groove. A ring of this construction provides a circumferentialseries of openings or oil drainage passages 9 between the inner andouter convolutions of the unitary ring. In the slightly varied form ofthe ring shown in Fig. 4, the attached ends of the flat outerconvolutions I and 2 are integrally connected with the adjacent ends ofthe arched inner convolution by integral uniting portions I and II. Thelength of the connecting portion Il) is equal to the combined length ofthe connecting portion `6 and the adjacent connecting portion and thelength of the connecting portion II is equal to the combined length ofthe connecting portion 8 and the adjacent connecting portion 5. Thisarrangement eliminates the separate bends providing the spacedconnecting portions 6 and 8 of the ring shown in Fig. 1.

'I'he two-piece ring shown distended in Fig. 5 is made of two sectionsof a fiat steel strip rolled or coiled to form a number of convolutionsincluding two flat side or end convolutions I and 2 and at least oneintermediate convolution having integral connection with the endconvolutions, respectively. A part of the intermediate convolution isintegrally connected with each of the side convolutions, and theadjacent ends of said intermediate convolution have laterally extendedabutments I2 which prevent the arch portions 3' from becoming overlappedor sliding one beyond the other when the ring is placed in the ringgroove 'I of the piston. With the exception that the ring shown in Fig.5 is made in two parts and includes the abutments I2, said ring is thesame as that shown in Fig. 1. The abutments I2 extend laterally towardthe adjacent side convolution to cooperate with the connections 5' inspacing the side convolutions I' and 2. A

The ring shown in Figs. 6 and 7 is made of a strip of fiat steel coiledto provide two flat side or end convolutions I3 and I4 integrallyconnected with an intermediate convolution having an annular series oflateral arches or bends to hold the side or end convolutions properlyspaced. The intermediate or spacer convolution of this unitary ringincludes a number of circumferentialiy alined relatively long atportions I5 for contacting one `of the side convolutions and integrallyconnected by relatively short arches or bends I6. The bends or arches I6are wider at the outer periphery of the ring than at the inner peripheryof the ring and are shaped and formed in such a manner that, when thering is under compression within a cylinder, the outer peripheralportions I'I of said arches are in continuous annular alinement with theouter periphery of the composite ring and do not extend outwardly beyondthe outer periphery of any portion of the ring when the peripheries ofthe convolutions I3 and I4 and of the elongated portions I5 of the innerconvolution are even with each other. This relationship may be attainedby dying the intermediate portion of the unitary ring to compress orforce the arches I6 slightly inwardly toward the axis of the ring toprovide the necessary tolerance required to obtain the relationshipshown in Fig. '1, in which the outer peripheries of all of the ringsegments or convolutions are on the same radius of curvature.Specifically, for the attainment of this relationship, the arches I6 maybe made wider at the outer periphery of the inner convolution than atthe inner periphery thereof, and also of slightly greater depth as shownin Fig. 6.

The side convolution I3 is integrally united with the adjacent end ofthe inner convolution by an integral connection I8 inclining laterallyfrom the elongated portion I5 a distance equal to the height of theadjacent arch I6 plus the thickness of the ring material. By thisarrangement, the outer surface of the outer convolution I3 is in thesame plane when the ring is compressed as shown in Fig. '7, which is itsposition when mounted in a piston groove. Similarly, the outerconvolution I4 is united with the ad1 jacent end of the innerconvolution by an integral connection I9 inclining laterally from theportion I5 a distance equal to the thickness of the strip of which thering is composed so that, when the ring is tted in a piston groove, theouter surface of the convolution I4 is uniformly in the same plane. Aring of this construction includes circumferential series of openings oroil passages 20 and 2| between the inner and outer convolutions of thering. In the slightly varied form of this unitary ring shown in Fig. 9,the lateral extension 22 is equal to the height of the `arches I6 andhas a circumferentially extended portion 23 to constitute a side rest orbearing for the end of the convolution I3. The convolution I3 isintegrally united with the extension 23 by a portion 24 extendinglaterally a distance equal to the thickness of the ring material.

In the two-piece ring shown in Figs. 10 and 11, the convolution I4 isintegrally united with the inner convolution by an offset bend 25extending laterally a distance equal to the height of the arches 26 plusthe thickness of the metal so that, when the ring is compressed as inFig. 11 with the outer convolution I4' against the arches 2B, the outersurface of said outer convolution is in the same plane throughout. 'Iheopposite end 2'I of the inner convolution is separated from theconnection 25 a suilicient distance to receive between said parts alaterally bent portion 28 formed diametrically opposite from the ends ofthe separate outer ring portion 29 which, when the ring is assembled,seats against the circumferentially elongated parts 30 of theintermediate or spacer convolution. When assembled as shown in Fig. 11,the bend 28 extends substantially into the space between the connection25 and the end 21, and thereby limits extent of relative turningmovement of the two ring parts.

Each specific embodiment of the invention disclosed is composed ofcoiled thin steel of uniform axial thickness and uniform radial widththroughout, and includes two outer annular portions each of less lengththan a complete annulus and each having lts outer surface in a singleradial plane throughout its circumference. A spacer convolution islocated between and may be integrally connected with one end of each ofsaid outer portions as in Figs. 1 and 6, or with only one of said outerannular portions as in Fig. 10. In each embodiment, the spacerconvolution comprises an annular series of arcuate circumferentiallyelongated at segmental portions curving transversely on the saine radiusof curvature as said outer portions and each having one fiat sidebearing throughout its length against the inner radial surface of one ofthe outer portions. These elongated at segmental portions that curvetransversely on the same radius of curvature as the outer portions areindicated by l (Fig-1) by l (Fig. 6), and by 3i! (Fig. l0).

' An annular series of arches 3 5 iFig. 1), ll-IG (Fig. 6), yand 26(Fig. 10) integrally connect the respective segmental portions andcontact at spaced intervals with the radial inner side of the otherouter portion of the ring. 'I'he sides of these respective archesconverge from the segmental portions and are of relatively much lesslength than the circumferential length of said segmental portions, andthe arches thus provided cooperate with the elongated segments of thespacer convolution to hold the two outer annular portions of the ring inspaced. relationship. By making the spacer convolution of elongated fiatsegmental portions integrally connected by arches; less material isrequired than would be required if the arches were close to-'- getherand the elongated segments were omitted. Further, by providing thearches with sides that converge from these segmental portions, maximumresiliency is obtained to facilitate tting the rings in the pistongrooves. The resiliency 'is greater than if the sides of the archesextended at right angles to the elongated at portions.

Either form of the invention as disclosed in the drawings is adapted foruse on a piston having the piston ring groove l therein. When the ringis mounted in the groove l, the outer surfaces of the outer annularportions of the ring are pressed into close sealing contact with theside walls of the groove and the peripheral portions of all ringconvolutions will be pressed against the wall of the cylinder 3l andprevent the passage of gas from the combustion chamber and also preventthe passage of oil into the combustion chamber of the engine. Anexpanding ring 32 to cooperate with either specic form of piston ringdisclosed may be mounted within the piston ring groove l. The combinedthickness of the several convolutions, including the arches or bends onthe spacer convolution, is slightly greater than the width of the groove1, so that the entire composite ring must be slightly compressed inorder to enter the groove.

The invention may be varied in other specific forms without departurefrom the nature and principle thereof.

I claim:

1. A multiple piece piston ring composed of a plurality of coils of thinsteel and including two outer annular portions each of lesscircumferential length than a complete annulus having their outersurfaces in single planes throughout their circumferences, a spacerconvolution of less circumferential length than a complete annulusunattached to one of said annular portions and having integralconnection with the other and having a circumferential series of lateralarches holding said annular portions in spaced relationship and formingpassages, and means preventing substantial turning of said unattachedannular portion with respect to said spacer convolution and leaving saidtwo outer portions free to expand and contract during movement of thepiston on which they are mounted.

2. A. piston ring composed of coiled thin steel of uniform axialthickness and uniform radial Width throughout and including tworelatively unattached outer annular portions each of lesscircumferential length than a complete annulus and each having its outersurface in a single radial plane throughout its circumference; a spacerconvolution integrally connected with one end of only one of saidportions and unattached to the other and comprising an annular series ofarcuate circumferentially elongated ilat segmental portions curvingtransversely on the same radius of curvature as said outer portions andeach having one at side thereof bearing throughout its length againstthe inner radial surface of only one of said outer portions, and anannular series of arches integrally connecting said segmental portionsand contacting at spaced intervals with the radial inner side of onlythe other outer portion of said ring, the sides of said respectivearches converging from said segmental portions and being relatively ofmuch less length than the circumferential length of said segmentalportions, and said spacer convolution thereby holding said two outerportions of the ring in spaced relationship.

3. A piston ring composed of two relatively unattached coils of thinsteel of uniform axial thickness and-*uniform radial width throughouttheir lengths, each being of less circumferential length than a completeannulus, and each having its inner `and outer surfaces in single flatradial planes throughout its circumference; a spacer convolution betweensaid two coils integrally attached to one of said coils and unattachedto the other coil and comprising an annular series of arcuatecircumferentially elongated ilat segmental portions curving transverselyon the same radius of curvature as said two coils and each having one atside thereof bearing throughout its length against the inner nat radialsurface 'of one of said coils, an annular series of laterally extendedarches integrally connecting said segmental portions, said archesengaging the inner ilat radial surface of the other coil and holdingsaid coils in spaced relationship and cooperatsides of said respectivearches converging from and being relatively of much less length than thecircumferential length of said segmental portions, and means preventingsubstantial turning of said unattached coils with respect to each otherand said spacer convolution.

EDWARD B. ROTHWEILER..

